Broken line making attachment for draftsmen&#39;s scales



Sept. 9, 19 7, D. G. JACKSON ,427,143

BROKEN LINE MAKING ATTACHMENT FOR DRAFTSMEN'S SCALES Filed NOV. 13, 1944 arrow/n:

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, carriage is a fiat portion 22 which Patented Sept. 9, 1947 UNITED STATES PATENT OFFICE BROKEN LINE MAKING ATTACHMENT FOR DRAFTSMENS SCALES I Donald Gordon Jackson, Pasadena, Calif. Application November 13, 1944,, SerialNo; 563,135

' (o1. s3 s9) 4 Claims.

My invention relates to the art of making drawings and, it is particularly. useful in the art of mechanical drafting, although it can be used for other purposes. In making working and other drawings of machinery; tools, and the like it is highly desirable that lines used to define dimensions be made of broken or interrupted lines and is an object of my invention to provide a tool by which said broken or interrupted lines maybe produced, each portion of said line andtho spaces therebetween being of equal length. Further objects and advantages will be made evident hereinafter.

In the drawing, which shows a preferred form of my invention:

Fig. 1 is an elevation showing how my invention is used;

Fig. 2 is an elevation at right angles to Fig. 1 viewed in the direction of the arrow 2 of Fig. 1;

Fig. 3 is an elevation of my tool viewed in the direction of the arrow 3 of Fig. 1;

Fig. 4 is a view of the cam wheel;

Fig. 5 is plan view of my tool as seen from above;

Fig. 6 is an enlarged cross-sectional View taken in the direction of the arrows B5 of Fig. 3; and

Fig. '7 shows one kind duced by my tool.

The preferred form of my invention shown in the drawing consists of a carriage I| preferably formed of a metal or plastic sheet. It may be adapted to be used with a conventional draftsmans scale I2 whose section is an equilateral triangle having grooves IS in the sides I4 thereof. The carriage is so formed that it extends over the top of the scale and has prongs I5 which project into the grooves I3 and thus restrain the movement of the carriage II to a straight line parallel to the ruling edge ll of the scale I2.

The carriage II has a housing I8 carrying a wheel 20 turning on a shaft 2|. Between the housing I8 and the scale-engaging portion of the has an opening 23 therein. This opening may be wedge-shaped with rounded ends, as shown in Fig. 6, and is symmetrical about a line defined by a guide line 24 scribed on the top of the flat portion 22.

The housing I3 is shown in Fig. 6, to enclose the wheel 20, the top 25 of the housing I 8 forming a convenient rest for the right hand 26 of the user, whose left hand 27 holds the scale I2 in the desired position.

The tool is used in the following manner. The carriage II is placed on the scale I2, in the posiof line that may be propreferably bent over, as

tion. shown in Fig. 1 and Fig. 2, with the scribed line 24 on the described locus of the broken line and. with the edge It parallel to this. desired. line. The user grasps a marking implement, for eX- ample,. the pencil 30, in his right hand 26,. his left hand. 21 holding the scale firmly in position. The user. then inserts the pencil 30 in. the groove 23', resting his hand. 26 on the. top 25 of the housing I8 of the carriage I I. The user exerts sufiicient downward. pressure on the top 2 5 to hold the wheel2i1in good contact with the surfacefl, which may be covered with paper or tracing cloth.

The wheel 2|] may have various forms, one such form, shown in Fig. 4, being cylindrical about the axis of the shaft but having four teeth or ridges 32 formed thereon. This wheel produces the line shown in Fig. 8 and by varying the form of the wheel 20 and its teeth 32 lines of different appearance may be drawn.

As the user moves the carriage I I along the scale I 2, holding the wheel 20 in contact with the surface 3|, the wheel rotates and the teeth 32 periodically lift the pencil 30 from the surface 3|, leaving the spaces 35 seen in the line shown in Fig. 7.

This tool has several uses but it has a special utility for draftsmen making drawings having broken dimension lines. By its use a draftsman can draw very uniform broken lines as fast as he can draw continuous ones. Uniformity in these lines seems to be very important to some people such, for example,'as the army and navy, who are quite insistent on uniformity in many things.

The carriage II is of relatively thin and therefore flexible material, and it fits rather loosely on the scale. Due to this loose fit and the flexibility of the material, the cam wheel 29 has no difficulty in lifting the point of the pencil from the paper. The purpose of the wedge-shaped opening 23 is to accommodate different sizes of leads.

I claim as my invention:

1. A device for ruling interrupted lines on a surface, comprising: a carriage having an opening through Which a marking implement can extend and a rest for a hand holding said implement; a straight edge for guiding said carriage in a straight line; and a cam wheel upon which said carriage is supported on said surface, said cam wheel being so formed that as it rolls over said surface it periodically lifts said writing implement in a direction at a right angle to said surface, thus interrupting the line being scribed by said marking implement.

2. A device for ruling interrupted lines on a surface, comprising: a carriage having an opening through which a marking implement can extend and a rest for a hand holding said implement; a straight edge for guiding said carriage in a straight line, said carriage extending over said straight edge and contacting the top and two sides thereof so that the carriage can move only in the direction of the ruling edge of said strai edge; and a cam wheel upon which said carriage is supported on said surface, said cam wheel being so formed that as it rolls over said surface it periodically lifts said writing implement in a direction at a right angle to said surface, thus interrupting the line being scribed by said marking implement.

3. A device for ruling interrupted lines on a surface, comprising: a carriage having a wedgeshaped slot through which a marking implement can extend and a rest for a hand holding said implement; a straight edge for guiding said carriage in a straight line; and a cam wheel upon which said carriage is supported on said surface, said cam wheel being so formed that as it rolls over said surface it periodically lifts said writing implement in a direction at a right angle to said surface, thus interrupting the line being scribed by said marking implement.

4. A device for ruling interrupted lines on a plement in a direction at surface, comprising: a carriage having a wedgeshaped slot through which a marking implement can extend and a rest for a hand holding said implement; a straight edge for guiding said carriage in a straight line, said carriage extending over said straight edge and contacting the top and two sides thereof so that the carriage can move only in the direction of the ruling edge of said straight edge; and a cam wheel upon which said carriage is supported on said surface, said cam wheel being so formed that as it rolls over said surface it periodically lifts said writing ima right angle to said surface, thus interrupting the line being scribed by said marking implement.

DONALD GORDON JACKSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 81 L861 Mertes Apr, 17, 1906 891,810 Berglind June 30, 1908 1,888,305 Berger Nov. 22, 1932 FOREIGN PATENTS Number Country Date 587,609 Germany Nov. 6, 1933 

